"Access violation reading location" troubles retrieveing buffer from directx

The problem I am having is with the following

ID3D10Texture2D *pBackBuffer;

hr = mpSwapChain->GetBuffer(0, __uuidof(ID3D10Texture2D), (LPVOID*) &pBackBuffer);

Below is my code...

#include "DX3dApp.h"




bool DX3dApp::Init(HINSTANCE hInstance, int width, int height)
{
    mhInst = hInstance;
    mWidth = width;
    mHeight = height;

    if(!WindowsInit())
    {
        return false;
    }
    if(!InitDirect3D())
    {
        return false;
    }

    return true;
}

int DX3dApp::Run()
{
     MSG msg = {0};

     while (WM_QUIT != msg.message)
    {
        while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE) == TRUE)
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }

        Render();
    }

    return (int) msg.wParam;
}

bool DX3dApp::WindowsInit()
{
    WNDCLASSEX wcex;

    wcex.cbSize = sizeof(WNDCLASSEX);
    wcex.style          = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = (WNDPROC)WndProc;
    wcex.cbClsExtra     = 0;
    wcex.cbWndExtra     = 0;
    wcex.hInstance      = mhInst;
    wcex.hIcon          = 0;
    wcex.hCursor        = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground  = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName   = NULL;
    wcex.lpszClassName  = TEXT("DirectXExample");
    wcex.hIconSm        = 0;
    RegisterClassEx(&wcex);

    // Resize the window
    RECT rect = { 0, 0, mWidth, mHeight };
    AdjustWindowRect(&rect, WS_OVERLAPPEDWINDOW, FALSE);

    // create the window from the class above
    mMainhWnd = CreateWindow(TEXT("DirectXExample"), 
                             TEXT("DirectXExample"), 
                             WS_OVERLAPPEDWINDOW,
                             CW_USEDEFAULT, 
                             CW_USEDEFAULT, 
                             rect.right - rect.left, 
                             rect.bottom - rect.top, 
                             NULL, 
                             NULL, 
                             mhInst, 
                             NULL);
   if (!mMainhWnd)
   {
      return false;
   }

   ShowWindow(mMainhWnd, SW_SHOW);
   UpdateWindow(mMainhWnd);

   return true;
}

bool DX3dApp::InitDirect3D()
{
    DXGI_SWAP_CHAIN_DESC scd;
    ZeroMemory(&scd, sizeof(scd));

    scd.BufferCount = 1;
    scd.BufferDesc.Width = mWidth;
    scd.BufferDesc.Height = mHeight;
    scd.BufferDesc.Format = DXGI_FORMAT_B8G8R8A8_UNORM;
    scd.BufferDesc.RefreshRate.Numerator = 60;
    scd.BufferDesc.RefreshRate.Denominator = 1;
    scd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
    scd.OutputWindow = mMainhWnd;
    scd.SampleDesc.Count = 1;
    scd.SampleDesc.Quality = 0;
    scd.Windowed = TRUE;

    HRESULT hr = D3D10CreateDeviceAndSwapChain(NULL,D3D10_DRIVER_TYPE_REFERENCE,
                                                NULL,
                                                0,
                                                D3D10_SDK_VERSION,
                                                &scd,
                                                &mpSwapChain,
                        开发者_C百科                        &mpD3DDevice);

    if(!hr != S_OK)
    {
        return FALSE;
    }

    ID3D10Texture2D *pBackBuffer;

    hr = mpSwapChain->GetBuffer(0, __uuidof(ID3D10Texture2D), (LPVOID*) &pBackBuffer);

    return TRUE;
}

void DX3dApp::Render()
{

}


LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message) 
    {
        // Allow the user to press the escape key to end the application
        case WM_KEYDOWN:
            switch(wParam)
            {
                // Check if the user hit the escape key
                case VK_ESCAPE:
                    PostQuitMessage(0);
                break;
            }
        break;

        // The user hit the close button, close the application
        case WM_DESTROY:
            PostQuitMessage(0);
        break;
    }
    return DefWindowProc(hWnd, message, wParam, lParam);
}

and I get the following error

chp1.exe': Unloaded 'C:\Windows\SysWOW64\oleaut32.dll'
First-chance exception at 0x757ce124 in chp1.exe: Microsoft C++ exception: _com_error at memory location 0x0018eeb0..
First-chance exception at 0x757ce124 in chp1.exe: Microsoft C++ exception: _com_error at memory location 0x0018edd0..
First-chance exception at 0x757ce124 in chp1.exe: Microsoft C++ exception: _com_error at memory location 0x0018ef1c..
The thread 'Win32 Thread' (0xfc4) has exited with code 0 (0x0).
'chp1.exe': Unloaded 'C:\Windows\SysWOW64\D3D10Ref.DLL'
First-chance exception at 0x00b71894 in chp1.exe: 0xC0000005: Access violation reading location 0x00000000.
Unhandled exception at 0x00b71894 in chp1.exe: 0xC0000005: Access violation reading location 0x00000000.

It appears that the error occurs in the last parameter. &pBackBuffer. I added this single line of code and the error occurs.

[edit]

as stated below , the issue is I am accessing a null pointer to buffer. but i have no idea what I am doing wrong with creating it.

---

This error means you accessed a NULL pointer. Most likely, mpSwapChain is NULL.

Edit:

Your check of hr isn't performed correctly: It should be if (hr != S_OK) instead of if (!hr != S_OK).

A better way to check hr is: if (FAILED(hr)) (or SUCCEEDED(hr) when checking for success). This is better because there are some successful values of hr which aren't S_OK.

---

Figure out my issue. The problem is the following line of code

scd.BufferDesc.Format = DXGI_FORMAT_B8G8R8A8_UNORM;

I put in the incorrect format for the buffer. This almost resembles

scd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;

So like interjay said. when a error like that consist. more then likely its problem something that cause the SwapChain not to be initiated. which more then likely is a logical error.